DESIGN OF WIND TURBINE BLADE

Wind turbines have now become one of the fastest growing forms of new electricity generation worldwide. In order to meet evolving mission needs in the area of wind power, it comes as no surprise that much of today's wind power research focuses on improving blade design of wind turbine, since this forms the critical part to yield more energy. Wind turbine blades, presently designed for 40 to 30m length or less. Since a turbine with long blades can capture more of the energy in the wind and therefore generate more electricity than a turbine with shorter blades, our study will consider a composite blade of 50m length.

Methodology used is Blade Element Moment theory which is theoretical method to calculate performance of wind turbine, Fluid structure interaction for coupled field analysis; CFD is used to determine aerodynamic loads and turbulence models are also used. Tools used are ANSYS classic, ANSYS CFX, FLUENT, and GAMBIT, GH Bladed.

Here we strive to determine the Total power developed and the aerodynamic load acting on blades during stall and rotating condition and thereby determining the stress and deflection of blade.

In order to achieve lower cost per kW using wind turbine the size of wind turbine nowadays has increased dramatically. With modern computing facility and available memory complex model can be generated and analyzed easily. In this project, we have done design and analysis of wind turbine blade with 50m radius.

Types of Wind turbine Wind turbines can be categorized into two overarching classes based on the orientation of the rotor.

1 Vertical Axis wind turbine

2 Horizontal Axis wind turbine

The portion of the wind turbine that collects energy from the wind is called the rotor. The rotor usually consists of two or more wooden, fibreglass or metal blades which rotate about an axis (horizontal or vertical) at a rate determined by the wind speed and the shape of the blades. Also it consists of extenders that attach the blades to the central hub and Pitch drives to control the angle of the blades.

Nacelle is the housing on top of the tower, which contains Generator, Gear-box, High-speed and low-speed shaft, controls and brake assemblies inside it. Generator converts the turning motion of a wind turbines blade into electricity. Inside the generator coils of wire are rotated in a magnetic field to produce electricity. Generators typically require rpm’s of 1200 to 1800. As a result most wind turbines require a gear-box transmission to increase the rotation of the generator to the speeds necessary for efficient electricity production. Brakes are used to stop the rotation of the rotor at storm wind conditions and during maintenance.

The tower on which a wind turbine is mounted is not just a support structure. It also raises the wind turbine so that its blades safely clear the ground and so it can reach the stronger winds at higher elevations. Maximum tower height is optional in most cases, except where zoning restrictions apply. The decision of what height tower to use will be based on the cost of taller towers versus the value of the increase in energy production resulting from their use.

SCOPE OF THE STUDY

Turbine blades experience variable aerodynamic loads, potentially causing adverse effect on structures, mechanical components and power production. The study carried out on a 50m radius blade gives a good understanding of the loads experienced and can be evaluated for further developments of wind turbines.

Aerodynamic analysis is done using BEM theory and stress distribution is done using conventional decoupled method and FSI for parked condition of blade and decoupled analysis is done for operating condition.

Our present study concentrates on designing a wind turbine blade of 50m radius and carry out aerodynamic analysis and also to predict the stress distribution over the blade during the operating conditions and during gust condition when the rotor blade is parked.

FSI and decoupled analysis are used for prediction of deflection and stress under parked condition

Decoupled analysis is used for prediction of stress under operating conditions.